Error on line 1, column 1 of pubspec.lock: Unexpected character

The file pubspec.lock is a generated file, so you can delete it and then regenerate it.

Delete pubspec.lock.

Run the following command:

flutter pub get

or

flutter pub upgrade

Notes on pub upgrade (you could probably skip the delete step).

Delete the file at flutter/packages/flutter_tools/pubspec.lock then try flutter pub upgrade again.

You may have interrupted the upgrade process before it finished hence the file became invalid.

I took the same error, but this error was coming from my main folder. in this path "C:\Users"yourusername"\AppData\Local\Pub\Cache\global_packages\devtools" I deleted the file and I started app. file has been by itself created and problem solved.

I got the same error while working.

I deleted pubspec.lock file.

then I ran command

flutter pub get

It created new pubspec.lock file.

Now application runs without any errors.